E-Skip: Difference between revisions
(added info about eskip and sporadic eskip. diagram needed?) |
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* time frames for communications are predictable | * time frames for communications are predictable | ||
* QSB (fading) is slow and predictable | * QSB (fading) is slow and predictable | ||
=== At which frequencies does E-Skip occur? === | === At which frequencies does E-Skip occur? === | ||
E-Skip generally occurs at night in the medium and shortwave [[HF]] parts of the spectrum. | E-Skip generally occurs at night in the medium and shortwave [[HF]] parts of the spectrum. | ||
===Sporadic E-Skip === | ===Sporadic E-Skip === | ||
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* fast and unpredictable QSB (fading) events | * fast and unpredictable QSB (fading) events | ||
===Further reading=== | |||
* [http://www.amfmdx.net/propagation/Es.html Mid latitude sporadic E (ES) - A review] | |||
* [http://en.wikipedia.org/wiki/TV_and_FM_DX#Sporadic_E_propagation_.28E-skip.29 Wikipedia article] | |||
{{propagation}} | {{propagation}} | ||
Latest revision as of 17:04, 9 November 2010
Related wiki pages : Propagation, Meteor scatter, Aurora, Tropospheric ducting
What is it?
The E-layer is the lowest layer of the atmosphere and can typically be found at altitudes between about 80km and 100km. the E-Layer is characterised by high electron densities, and high temperatures (between 300K and 122K)
E-Skip propagation is the reflection of radio waves off the E-Layer, allowing reception many thousands of kilometres distant from normal reception areas.
E-Layer communications are characterised by:
- weaker but longer paths than usual
- directions for optimal communications, and hence target areas are predictable
- time frames for communications are predictable
- QSB (fading) is slow and predictable
At which frequencies does E-Skip occur?
E-Skip generally occurs at night in the medium and shortwave HF parts of the spectrum.
Sporadic E-Skip
Sporadic E-skip is associated with scattered regions of especially dense ionisation that occur seasonally within the E-layer. generally it occurs:
- daily during the day in equatorial regions
- commonly in temperate regions in late spring, early summer and sometimes in early winter
- in association with auroras in Polar regions
- at frequencies up to about 150MHz
- can provide communication over distances up to 2,400Km
Sporadic E-Skip is characterised by:
- strong, relatively short paths
- unpredicatable times
- unpredictable directions
- fast and unpredictable QSB (fading) events
Further reading
| Propagation and radio wave theory | |
| Propagation | Aurora * E-Skip * IPS * Lightning scatter * Meteor scatter * Satellites * Trans-Equatorial Propagation * Tropospheric ducting |
| Interference | QRM * QRN |
| Theory | Electromagnetic Waves * Frequency Wavelength and Period |